vsphere storage appliance工作原理和实施

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　　摘录自：http://www.07net01.com/storage_networking/VMwarexunihuazhiVSA_vSphere_Storage_Appliance_qunji_yi_bushuxiang_93154_1363875290.html
　　Windows XP is designed to support dual and multi-core processors from version Service Pack 2 and later.
Physical memory limits[edit]
　　Maximum limits on physical memory (RAM) that Windows XP can address vary depending on both the Windows version and between 32-bit and 64-bit versions.[99][100] The following table specifies the maximum physical memory limits supported:
Physical memory limits in each Windows XP edition[99][100]   Version Maximum RAM supported  Windows XP Professional 4 GB  Windows XP Home Edition  Windows XP Media Center Edition  Windows XP Tablet PC Edition  Windows XP Starter Edition 512 MB  Windows XP Professional x64 Edition 128 GB
Processor limits[edit]
　　The maximum total number of logical processors[101] in a PC that Windows XP supports is: 32 for 32-bit;[102][103] 64 for 64-bit.[104][105]
　　The maximum number of physical processors in a PC that Windows XP supports: is 2 for Professional;[106] and 1 for the Home Edition.[107]
Physical memory limits for Windows 7[70]   Version Limit in 32-bit Windows Limit in 64-bit Windows  Windows 7 Ultimate 4 GB 192 GB  Windows 7 Enterprise  Windows 7 Professional  Windows 7 Home Premium 16 GB  Windows 7 Home Basic 8 GB  Windows 7 Starter 2 GB N/A Processor[edit]
　　The maximum total number of logical processors[71] in a PC that Windows 7 supports is: 32[72] for 32-bit, 256[73] for 64-bit.
　　The maximum number of physical processors in a PC that Windows 7 supports is: 2 for Professional, Enterprise, and Ultimate, and 1 for Starter, Home Basic, and Home Premium.[74]

　　VMware vSphere Storage Appliance (VSA) 是包含 SUSE Linux Enterprise Server 11 和存储群集服务的VMware 虚拟设备。VSA 虚拟机在多个 ESXi 主机上运行，可对主机上安装的存储资源进行抽象并创建 vSphere Storage Appliance 群集（VSA 群集）。
　　VSA 群集利用多个 ESXi 主机的计算和存储资源，并提供一组可由数据中心中的所有主机访问的数据存储。
　　运行 vSphere Storage Appliance 并加入 VSA 群集的 ESXi 主机是 VSA 群集成员。通过vSphere Storage Appliance，您可以创建具有两个或三个 VSA 群集成员的 VSA 群集。仅在半数以上的成员处于联机状态时，VSA 群集的状态才为联机。
　　VSA 群集可实现以下功能：
1.为数据中心中的所有主机提供共享数据存储
2.提供每个共享数据存储的副本
3.vSphere vMotion 和 vSphere HA
4.硬件和软件故障切换功能
5.替换出现故障的 VSA 群集成员
6.恢复现有的 VSA 群集

　　二、前提条件：
部署前，我们先要认真了解VSA群集对硬件的要求，要知道，虚拟化的应用，尤其是VMware的虚拟化对硬件平台的条件要求都是非常苛刻的，所以我们还是最好先了解清楚VSA群集的硬件要求。
下表列出了VSA群集对ESXi主机的要求，这些要求很关键：